Reactor for nuclear fusion



Dec. 10, 1963 G. J. LINHART 3,113,917

' REACTOR FOR NUCLEAR FUSION Filed Nov. 28, 1960 1 1 lo 1 I I5 /Jf D E 454 2 y A2 23 Q4 ls zo INVENTOR GEORGE JIRI LINHART ATTORNEYS .Various processes have hitherto been United States Patent 3,113,917 REACTOR FOR NUCLEAR FUSION George .Iiri Linhart, Via Di Sale, Fracati, Italy Filed Nov. 28, 1960, Ser. No. 72,026 Claims priority, application Belgium Dec. 3, 1959 1 Claim. (til. 204-1%.2)

It is known that the fusion of certain nuclei is accompanied by the liberation of a large amount of energy. However, an intense source of heat, capable of producing a temperature of the order of several million degrees, must be available in order to initiate such a reaction. used in an attempt to obtain this high temperature. Reference may be made in particular to the process in the hydrogen bomb, which produces energy but cannot be regulated in order to obtain usable energy. Concentrated electrical discharges, known as pinch, which are caused to pass through suitable gaseous mixtures may also be used. Experiments which have been carried out with various forms of concentrated electrical discharges have revealed a certain number of disadvantages, more particularly lack of stability in the discharge, enormous losses of energy and lack of resistance of materials subjected to extremely high temperatures.

In a large number of devices which have already been developed, such as that diagrammatically illustrated in FIGURE 3 of the article by Clauser et al., Proceedings of the Second United Nations International Conference on the Peaceful Uses of Atomic Energy, volume 32, United Nations, Geneva, 1958, page 163, the sudden application of a high voltage between two electrodes breaks down the insulator formed by a column of gas. Because of the skin effect, the discharge current I is concentrated chiefly on the periphery of the said column. This layer of current contracts under the action of the azimuthal magnetic field Be. During the said contraction, it encounters neutral gas molecules, imparts a certain amount of energy to them and ionises them. This retards movement of the layer of current and prevents the discharge from attaining high kinetic energy through its particles, from contracting to a smaller radius and from producing a positive energy balance.

The following theoretical considerations will serve to analyse the causes of this lack of success.

Assume a cylinder of deuterium and tritium plasma, having a radius R, and a density n It will be assumed that the plasma has been raised by suitable means to a temperature of 0.5.10 K., at which the reaction (D, T) occurs at optimum velocity. The mean thermal agitation velocity of the nuclei D and T is then approximately 10 cm./ sec. In the absence of any additional contribution of kinetic energy, the plasma cools because of losses, and increases in volume while Working against all the guiding fields which can be placed in opposition to it.

If no guiding field were used, the plasma would spread radially at velocity w. If a guiding field is used, this velocity is reduced to:

in which expression x may be called the guiding quality factor. The probability p of a reaction (D,T) during the life of a plasma is:

in which expression MN is the mean free path between two reactions in a plasma of density n MN is given by the following expression:

3,1 l3,9 l 7. Patented Dec. 10, 1963 ice in which expression N is the linear electron density, k is Boltzmanns constant, and T the temperature in degree absolute. The energy supplied by the fusion reaction is at most, 0.5N.p.Q, in which expression Q-2.8. 10' erg/ reaction The equation for a reactor giving power production will therefore be:

/2N.p.Q 3NkT or again Three conclusions may be drawn from this inequality: (a) N must be large,

(17) R must be small,

(0) X must be large.

This relationship must be modified when the discharge is subjected to a guiding magnetic field and when, after undergoing maximum contractions to a radius R the plasma increases in volume while working against the magnetic guiding field, and can thus recover a large part of its heat energy in the form of electromagnetic energy. Assuming that only the fraction 3NkT is lost during this action, I have N/R0 2.1O

in which expression on is the recovery factor.

The present invention relates to improvements in processes and devices for producing energy by nuclear fusion, and seeks to increase the efficiency of thermonuclear reactors, while mitigating the disadvantages enumerated above.

According to the present process, a cylindrical reactor, in which a high degree of vacuum has previously been set up, has introduced into it a gas or a mixture of gases through orifices situated in the curved wall of the reactor, and the said gas or mixture of gases, which takes the form of a cylindrical layer, is then subjected to an electrical discharge. The gas is preferably a mixture of deuterium and tritium. The vacuum which has been set up in the cylindrical reactor may be of the order of 10 mm. of mercury, and an applied potential may be used from a source producing an electrical discharge of the order of ten kilovolts. The gas or mixture of gases may advantageously be ionised before being introduced into the reactor.

The reactor for use in this process comprises a cylinder with circular ends, whereon the curved wall is of insulating material, preferably ceramic, and includes orifices.

A non-limitative example of the invention will be described hereinafter with reference to FIGURE 1 and FIGURE 2 of the appended drawing. FIGURE 2 represents a partial plan view of the device of the invention. FIGURE 1 represents a cross-section of the device of the invention along line A--B of FIGURE 2. In FIGURE 2 the perspective view is shown corresponding to that viewed along arrow C of FIGURE 1 and broken away along line DE of FIGURE 1. The devices which will be described in connection with this example must be considered as forming part of the invention without limiting it, it being understood that any equivalent variants may be used without departing from the scope of the invention.

In FIGURES 1 and 2 two circular electrodes 1 and 2 in the form of thin circular blades are attached to the inner parallel walls 24 and 25 of circular insulating material which form the ends of a cylindrical volume inside which the pressure is of the order of 10 mm. Hg. A high voltage source 18 supplying about ten kilovolts is connected to electrode 1 through the lead 17 and connected to electrode 2 through switch 19, the condenser 3 and the lead 20; the curved wall 10 of the cylinder is made of insulating material; this wall 10 includes a series of small orifices 11 situated at a distance R(12) from the central axis of symmetry 13 of the cylinder.

The device is enclosed in the annular insulating part 21 provided with four gas inlets 22.

A cylindrical layer of gas 14 is injected into the cylinder through the orifices 11 between the electrodes 1 and 2. This gas may be previously ionised, but ionisation will in any case take place when high potential from the source 3 is applied between the electrodes 1 and 2. When it is ionised, the said layer will be subjected to a force IB (arrow 15), wherein I is the value of the discharge current, and Bcp the field produced by this current. The layer of ionised gas will contract in the vacuum, and will not lose its kinetic energy. In addition the said layer will be radially compressed, and will attain a thickness 6 (16,

FIGURE 1) whereof the value is approximately:

161rN k T T T in which expression N is the number of electrons per square centimetre of surface area of the layer, k is Boltzmanns constant and T is the temperature of the plasma. Substituting the symbols by their value in the above equation:

N particles per 0111. T: 10 degrees K., B: 10 gauss one obtains 5-0.7 mm.

It follows from this that the minimum radius R of the concentrated electrical discharge (pinch) thus formed is of the same order of magnitude as 5, that is to say 1.5 to 2 mm.

A discharge is thus produced at very high temperature on the one hand because of the absence of loss by contraction against a gaseous medium, and on the other hand because of the very small radius of the concentrated electrical discharge.

I claim:

A reactor for nuclear fusion comprising a pair of spaced cylindrical electrodes, means for applying an electrical discharge between said electrodes, means for applying a high vacuum between said electrodes, a cylindrical insulating Wall between said electrodes forming a reaction chamber, said wall adapted to contain a low pressure atmosphere of a gas to be operated upon having small:

radial orifices situated therein uniformly around the en- 5 tire circumference of said wall, means for intermittently introducing a gas peripherally into said evacuated reaction chamber through said orifices, whereby a series of thin cylindrical layers of gas are formed between said electrodes which cylindrical layers of gas are radially compressed by said electrical discharge to the axis of said reaction chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,728,877 Fischer Dec. 27, 1955 2,902,614 Baker Sept. 1, 1959 2,961,558 Luce et al. Nov. 22, 1960 3,031,396 Anderson Apr. 24, 1962 FOREIGN PATENTS 841,792 Great Britain July 20, 1960 1,224,647 France Feb. 8, 1960 OTHER REFERENCES Proceedings of the Second United Nations International Conference on the Peaceful Uses of Atomic Energy, volume 32, United Nations, Geneva, 1958, pages 161- 164. 

